It is generally recognized that the use of animal models represents the most practical manner of studying the impact of diet upon the development of dental caries. While considerable progress has been made in recent years in the development of animal models for investigations of coronal caries, very little effort has been made to the development of similar procedures for investigating root surface caries. This proposed project is designed to develop an experimental animal model specifically designed to study root surface caries and to subsequently use this model to investigate the impact of a number of dietary factors upon root caries. The dietary factors which will be investigated will include different types, ratios and amounts of carbohydrate; the frequency of ingestion of carbohydrates and the interval between meals; decreased levels of dietary protein during adulthood; and the ingestion of varying ratios of calcium and phosphorus during adulthood. The hamster has been selected as the animal of choice based on a thorough review of the literature and the results from six previous studies which have been conducted by the investigators. The model will utilize the Konig-Hofer programmable feeder to control the amount and frequency of food ingestion as well as the interval between meals. The animals will be infected with a streptomycin-resistant strain of Actinomyces viscosus (alone or in combination with S. mutans) and the level of infection monitored quantitatively. The formation of root caries will be assessed using conventional microscopic examination procedures of murexide-stained molar teeth. The first 18 months of the project will be dedicated to the development of the experimental model and the remainder of the 3-year project will be used to study the role of dietary factors in the development of root caries. The results of this project will identify a practical animal model for studying root surface caries and determine the impact of a number of dietary factors on this disease.